Data centers can affect nearby water supplies through the water used to cool computing equipment and through the water consumed by power plants that generate their electricity. The scale and local consequences depend on the facility’s cooling system, water sources, operating schedule, utility capacity, drought conditions, and other users’ demand. Communities can assess those impacts before construction by asking for facility-specific estimates, planning for cumulative and peak demand, coordinating with utilities, and weighing water reuse and efficiency against energy, wastewater, reliability, and cost.
How a data center uses water
Servers and other computing equipment generate heat. A facility must move that heat outdoors to keep equipment within its operating range. In some systems, cooling towers reject heat by evaporating water into the air. The system also discharges some circulating water as blowdown to control the buildup of dissolved minerals. Makeup water replaces water lost through evaporation and blowdown.
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These flows are not interchangeable. A facility’s withdrawal is the water it takes from a source; its consumption is water that is not promptly returned to the same water system, often because it evaporates; its discharge is water released after use, potentially after treatment. A reported withdrawal therefore does not, by itself, establish how much water the facility consumes or what happens to its discharge.
Cooling towers can require substantial water, but a cooling system’s actual demand depends on cooling load, equipment and controls, and operating conditions. The U.S. Department of Energy’s Federal Energy Management Program describes opportunities including improving air management, using economizers where appropriate, managing cycles of concentration, and reusing cooling-tower blowdown through reverse osmosis. Its guidance is for federal data centers: it identifies technical opportunities, not guaranteed savings for every building.
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Direct and electricity-related water are different
Direct water use occurs at the facility—for example, water used to make up a cooling tower. There is also an indirect water footprint: power plants may withdraw or consume water to generate the electricity a data center uses. The size of that footprint depends on the power sources and their locations. A facility’s direct water-use figure does not capture the whole electricity-related footprint, and indirect estimates should not be mistaken for water measured at the data-center site.
In its 2026 report overview, Water Behind the Watts: The Hidden Risk of Powering Data Centers, Ceres estimates 3.4 trillion gallons of freshwater annually for electricity used by data centers in the seven states it analyzed: Virginia, Texas, California, Illinois, Georgia, Ohio, and Arizona. Ceres also estimates that 78% of electricity in those states came from power plants that use water. These are report estimates for that defined scope—not a facility-level measurement, a universal ratio, or a forecast for a particular community. USGS likewise cautions that direct-only measures omit much of the electricity footprint and that estimates vary with power generation and cooling technologies.
Why local conditions matter more than a single headline figure
There is no dependable universal water-use figure for a data center. Demand varies with facility size, computing density, cooling technology, site conditions, and how the facility operates. Regional estimates can help frame questions, but they cannot replace a proposed facility’s design information and local utility records.
The Interstate Commission on the Potomac River Basin (ICPRB) illustrates both the value and the limits of regional estimates. Its analysis of current demand in parts of the Potomac basin relied on aggregated average and peak use reported by Loudoun Water and Prince William Water and linked that use to identified facility power capacity. Where direct reporting was unavailable, ICPRB estimated use with a water-use-intensity factor. Its nominal site-level estimates range from 100 to 1,600 gallons per day per megawatt on average depending on cooling technology; it estimates peak use of up to 8,500 gallons per day per megawatt for evaporative cooling. These are methodology-dependent regional estimates, not a national benchmark or a substitute for a specific facility’s forecast.
To understand local exposure, establish where water would come from, how much is needed at average and peak conditions, and what other demands the same system must serve. A utility connection does not automatically mean a facility draws from one particular source: the supply may ultimately involve surface water, groundwater, reclaimed water, or a combination. A facility may also withdraw directly rather than receive all its water through a public utility.
Questions that make a local assessment concrete
- Source: Will the project use potable water, reclaimed wastewater, surface water, groundwater, or more than one source? Who controls each source?
- Timing: What are projected average and peak demands, and how do they change by season, operating load, or cooling conditions?
- System capacity: Can the relevant utility meet the project’s demand while serving existing users and other planned development?
- Water stress: What happens during drought, low flows, seasonal restrictions, or a disruption to the facility’s preferred source?
- Wastewater: How will blowdown or other process water be treated and discharged? Does reuse create a brine or other residual that requires management?
- Growth: Do estimates include planned expansion, concurrent projects, and the infrastructure required to serve them?
These questions matter because a large regional or statewide figure cannot establish that a particular project will cause household shortages, raise bills, or strain a specific utility. Those outcomes require local evidence about supply, infrastructure, rates, and cost allocation. Virginia’s Joint Legislative Audit and Review Commission (JLARC) discusses data-center resource and planning issues in Virginia; UC Berkeley’s Center for Law, Energy & the Environment (CLEE) examines reporting and policy in California. Their findings should not be treated as rules or conditions that apply nationwide.
What communities can do before and after approval
1. Request a facility-specific water plan
Before a site plan or permit is settled, ask the developer to disclose projected average and peak demand by source, cooling configuration, seasonal profile, drought response, wastewater and blowdown handling, and expansion assumptions. Require the estimates to identify the utility service area and the operating scenario they represent. Where possible, distinguish withdrawals, consumption, and discharge instead of relying on one undifferentiated “water use” number.
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Fix the driver behind crashes, sound loss and screen glitchesFind Drivers →Clear out junk files and repair common Windows errorsFree Scan →Scan for outdated or missing drivers - takes under a minuteDriver Scan →Planning-stage estimates give decision-makers a chance to consider long-term water and infrastructure effects before development is fixed in place. UC Berkeley CLEE recommends anticipated and actual water-use reporting regardless of source, together with site-specific information that helps local authorities compare a project with other uses.
2. Assess cumulative demand, not just one project
Ask water utilities and regional planners to evaluate concurrent data-center projects alongside homes, businesses, industry, and other planned development. The assessment should cover average and peak demand, low-flow and drought scenarios, seasonal variation, infrastructure capacity, and how costs for new or expanded infrastructure would be allocated. A project that appears manageable on its own may raise different questions when several projects depend on the same source or utility system.
ICPRB has called for greater transparency at daily time scales and flags potential supply and infrastructure pressure as data-center development grows in the Potomac basin. Its regional analysis is useful context for local planning, but a community still needs its utility’s information and the proposed project’s design assumptions.
3. Use the local processes available
Water impacts can be considered alongside energy and other infrastructure needs in siting, permitting, and zoning processes where local law allows. Communities should identify which bodies control land use, water withdrawals, utility service, wastewater, and drought response; those responsibilities may be divided across local, regional, and state agencies. JLARC describes Virginia’s state withdrawal oversight and the separate local question of how available water is shared among uses. The precise authority and process differ by jurisdiction, so a Virginia or California policy recommendation is not a nationwide legal requirement.
4. Ask for metering and ongoing public reporting
Where authorized, approval conditions or utility arrangements can require ongoing metering and reporting of actual use by source, with clearly defined average and peak periods. Communities can also ask how drought restrictions apply, how changes in cooling or operations affect demand, and whether reporting covers expansions as well as the initial facility. Forecasts help with approval; consistent operating data show whether actual demand matches the assumptions used in planning.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.How to compare cooling and water-supply options
Water-saving choices should be evaluated as a system rather than by a single “efficient” label. UC Berkeley CLEE notes that more water-efficient cooling can use more energy. DOE FEMP identifies operational and technical measures, including blowdown reuse, while noting that treatment such as reverse osmosis can add energy use and operating costs. A lower direct-water demand is not automatically the best overall outcome if it shifts burdens to electricity supply, wastewater treatment, or another resource.
For each feasible design or source, decision-makers can compare:
- Freshwater: How much potable water is withdrawn and consumed, including at peak conditions?
- Reliability: Is the supply dependable during drought, low flows, or maintenance interruptions?
- Energy: How much electricity does the cooling and treatment approach require, including at peak load?
- Wastewater: What volume and quality of discharge result, and how are blowdown, brine, and other residuals handled?
- Cost: What capital and operating costs are involved, and who pays for treatment, conveyance, and utility upgrades?
- Accountability: Can performance be metered, reported, and tied to enforceable operating or drought conditions?
Reclaimed water may reduce demand for potable supplies, but only if an appropriate source, treatment, conveyance infrastructure, and operating arrangements are available. Communities should ask what happens when reclaimed water is unavailable and whether the facility can switch to another source. Reuse is a site-specific option, not a universal substitute for utility planning.
What the Quincy, Washington, reuse project shows—and what it does not
The U.S. EPA’s Water Reuse Case Study: Quincy, Washington describes the Quincy Water Reuse Utility, a partnership between Microsoft and the City of Quincy. The utility treats cooling water and returns it for data-center cooling, reducing reliance on local potable groundwater. EPA estimates that the reuse treatment system saves 138 million gallons (522 million liters) of potable groundwater per year. The case study also reports use of 260 million gallons (984 million liters) per year of Columbia Basin Project canal water, primarily in summer.
That system took 10 years to plan, design, construct, and test, and EPA reports an overall project cost of $31 million. Those figures describe the Quincy project; they are not a cost or schedule forecast for other communities. The case study also notes that potable groundwater remains part of the system’s annual makeup supply, and that the project produces brine disposed of under state law. Its circular or reuse design therefore does not mean zero water use or zero residuals.
The project’s multiple sources also illustrate a resilience trade-off. During a 2021 period when canal pumps were shut off, the system could switch to potable groundwater. That backup helped maintain supply, but it underscores why communities should examine fallback sources and drought operating plans—not only the preferred source in normal conditions.
A practical checklist for community review
- Define the project: Identify proposed capacity, cooling configuration, expected operating conditions, and planned expansion.
- Trace the water: Identify every source, the utility or agency responsible, and whether water is potable, reclaimed, or another supply.
- Separate the metrics: Request withdrawal, consumption, discharge, average demand, peak demand, and seasonal estimates as distinct measures.
- Check the system: Compare demand with utility capacity, other users, planned development, drought plans, and environmental constraints.
- Test alternatives: Evaluate cooling efficiency and reuse alongside energy demand, treatment needs, wastewater effects, reliability, and cost.
- Set follow-through: Where authority permits, establish metering, public reporting, drought response, and review if actual use or expansion differs from the plan.
For a construction and land-use decision, the key is not whether data centers use water in the abstract. It is whether the proposed facility’s sources, demand profile, cooling design, backup arrangements, and cumulative effects have been made visible to the people responsible for local water and infrastructure planning.
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